| Project/Area Number |
06453198
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
自然地理学
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| Research Institution | Shinshu University (1996)
Tokyo Metropolitan University (1994-1995) |
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Principal Investigator |
SUZUKI Keisuke Shinshu University, Faculty of Science, Associate Professor, 理学部, 助教授 (60145662)
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| Co-Investigator(Kenkyū-buntansha) |
KOHSHIMA Shiro Tokyo Institute of Technology, Faculty of Science, Associate Professor, 理学部, 助教授 (60183802)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1994: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | winter precipitation / snow cover / snow meltwater / winter monsoon / sea salt / convective mixing layr / algae / microbiological activity / 寒冷積雪地 / 温暖積雪地 / 海塩起源物質 / 酸性化 / 融雪 / 河川流出 / 酸性化寄与物質 |
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| Research Abstract |
A chemical study of the winter precipitation was conducted in Tohkamachi, central Japan. The ratios of Cl^-/Na^+ and Mg^<2+>/Na^+ found in the winter precipitation samples were nearly equal to those of sea water. This result suggests that Na^+, Mg^+, and Cl^- found in the winter precipitation are originated from sea water. A relationship was determined between the Na^+ concentration in the winter precipitation sample and the height of the convective mixing layr. Cloud droplets containing sea salt particles are believed to be captured by snow crystals through the rain-out process. The results indicate that the higher the convective mixing layr heights, the larger the rate of collection of sea salt particles by the snow crystals. A relationship between the delta^<18>O values in the winter precipitation and the air temperature at the top of convective mixing layr was determined for several synoptic weather conditions which produced winter precipitation. The delta^<18>O values in samples p
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recipitated under conditions winter monsoon were found to be larger than those under other weather conditions at the same temperature. A good relationship is observed between the temperatures at the top of convective mixing layr and the delta^<18>O of samples of winter precipitation under conditions of the winter monsoon.
The variations of anion concentration and biological activity in the snow packs were studied at an open site, a deciduous forest site and a coniferous forest site. Concentrations of major anions in the snow pack are higher at the coniferous forest site than at both the open site and the deciduous forest site. Concentrations of major anions gradually decrease as the snowmelt progressed. Concentration of PO_3^<3-> in the snow pack increases as the snowmelt progressed. Concentration of chlorophyl-a in the snow pack is higher at the coniferous forest site than at both the open site and the deciduoud forest site. Concentrations of chlorophyl-a in the snow pack at both deciduoud and coniferous forest site increase during the snowmelt season. Activity of snow algae is considered to be actively during the snowmelt season. By the incubation experiment, NO_3^- of the sample collected at coniferous forest site is consumed probably by the snow algae. Consumption of nitrogen by Scenedesmus is estimated by the incubation experiment as 220 mg/l from the snow pack.
Chemical studies of the stream water in a small forested watershed were conducted at Aidzu-Tajima, Fukushima prefecture. The experimental watershed is located under the snowy temperate climate, and has an area of 0.14 km^2. The bedrock of the watershed consists of consolidated sediment formed in the Neogene. The watershed is entirely covered with forest vegetation. Maximum monthly precipitation is observed in summer ; however, maximum monthly runoff is recorded in snowmelt season. The HCO_3^- concentration of stream water is diluted by snow meltwater, and episodic increase of concentrations of Cl^-, NO_3^- and SO_4^<2-> is observed during the snowmelt season. The pH of stream water is lower during the snowmelt season than summer and autumn. The ionic composition of stream water is variable according to the seasons. Bicarbonate is the major anion in summer, and the ratio of Cl^-+NO_3^-+SO_4^<2-> increases in snowmelt season. Less
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